IDO & phenotypic switching of VSMC in transplant vasculopathy

描述（申请人提供）：移植血管病变（TV）是一种慢性血管疾病，其特征是由平滑肌样细胞（smlc）和相关基质组成的同心内膜过度扩张。急性移植排斥反应可以用最先进的免疫抑制疗法有效地预防和治疗，但目前还没有批准的医学干预措施来预防甚至延缓TV的发展。我们的初步数据首次揭示了smlc的过度增殖/合成和受损的凋亡是内膜过度扩张可能发生的细胞基础。值得注意的是，我们观察到来自内皮细胞（ECs）的吲哚胺-2,3-双加氧酶（IDO）可能通过上调vSMC分化特异性基因转录来下调SMLC的增殖/合成，并直接取消SMLC的抗凋亡特性。在补充的体内实验中，我们发现移植物内皮是内源性IDO诱导的主要部位，缺乏该基因的供体器官（而不是受体动物）更容易发生TV病变。根据这些新数据，我们假设内皮来源的IDO引导SMLC向更静息和分化状态的反向表型开关，并且移植物ECs中该酶的特异性过表达阻断了TV中的血管重塑。为了验证这一中心假设，我们开发了许多独特的动物模型和方法，其中包括小鼠心脏或肺电视模型和基于睡美人（SB）的非病毒基因整合策略，能够在移植物内皮内持久表达人IDO （hIDO）转基因。在特异性目标1中，我们将确定内皮细胞IDO对SMLC促增殖/合成特性的影响。在特异性目标2中，我们将确定内皮细胞IDO对SMLC抗凋亡特性的影响。在这些研究中，将探讨ido诱导smlc表型转换的可能分子机制。在特异性目标3中，我们将研究内皮细胞IDO增强在实验性TV的发展和逆转中的作用。在本研究中，内皮IDO对移植物功能和结构血管重构的可能有益作用将分别通过回声和组织学研究进行评估。这个项目产生的结果可能会为预防和治疗这种毁灭性疾病开辟一条新的途径，特别是考虑到基于sb的非病毒方法已经进入临床试验阶段。

DESCRIPTION (provided by applicant): Transplant vasculopathy (TV) is a chronic vascular disease characterized by concentric intimal overexpansion composed of smooth muscle-like cells (SMLCs) and associated matrix. Unlike acute transplant rejection that can be effectively prevented and treated with the state-of-the-art immunosuppression regiments, at present there is no approved medical intervention to prevent or even delay the development of TV. Our preliminary data, for the first time, revealed that excessive proliferation/synthesis and impaired apoptosis of SMLCs is a cellular basis by which intimal overexpansion may develop. Remarkably, we observed that indoleamine-2,3-dioxygenase (IDO) derived from endothelial cells (ECs) has the potential to down-regulate SMLC proliferation/synthesis via upregulation of vSMC differentiation-specific gene transcription, and directly abolish the anti-apoptotic property of SMLCs. In complementary in vivo experiments, we found that graft endothelium is the primary site for endogenous IDO induction, and that donor organs (but not recipient animals) lacking this gene are more susceptible to TV lesions. In light of these novel data, we hypothesize that endothelium-derived IDO directs a reverse phenotypic switch of SMLC towards a more quiescent and differentiated state, and that specific overexpression of this enzyme in graft ECs blocks vascular remodeling in TV. To test this central hypothesis, we have developed a number of unique animal models and approaches, which include mouse models of heart or pulmonary TV and the Sleeping- Beauty (SB)-based nonviral gene integrating strategy capable of long-lasting human IDO (hIDO) transgene expression within graft endothelium. In Specific Aim 1, we will determine the effect of endothelial IDO on SMLC pro-proliferative/synthetic properties. In Specific Aim 2, we will determine the effect of endothelial IDO on SMLC anti-apoptotic properties. In these studies, the possible molecular mechanism(s) behind IDO-induced phenotypic switch of SMLCs will be explored. In Specific Aim 3, we will examine the role of enhanced endothelial IDO in the development and reversal of experimental TV. In this study, the possible beneficial effect of endothelial IDO on functional and structural vascular remodeling in graft will be assessed by echo and histological studies, respectively. Results generated from this project may open a new avenue for the prevention and treatment of this devastating disease, especially given that the SB-based nonviral approach is already advancing into clinical trials.